Over the past two decades, the promise of accelerated drug development and personalized medicine have brought heighten attention to the field of biomarker. But do you really know what biomarker are, how they are developed, and how they are used?
Here, I'll share over 15 years of experience in the fields of biomarker development and translational research to try to answer some of these questions.

The key issue debated at this meeting is to determine the risk of this new type of testing to the public (the main mission of the FDA). Unlike traditional diagnostics which have a relatively clear and defined impact on the course of treatment for a patient on a short term basis, personal genetic testing is fundamentally a prognosis tool, opening the door to the ill-defined area of predictive medicine. Except for the specific genetic tests aimed at identifying the risk of responding favorably or unfavorably to a specific drug, genetic testing provides an estimate of the future risk of developing a specific genetically-linked disease or condition. Most of the genetic traits associated with genetically-linked diseases do not constitute an inexorable sentence for the patient since these traits are substantially influenced by the environment and with other genetic traits. For example, the presence of the mutated LRRK2 gene in ones genome carries a high risk of developing Parkinson’s disease at a relatively young age. However, among mutated LRRK2 carriers, there are individuals who have reached old age (> 80 year-old) who do not show any sign of Parkinson’s disease.

Since genetic testing as a prognosis for future disease does not immediately impact the safety of patients, what might be the risks associated with this new type of testing? At the personal level, I would argue that the main risk is psychological. Depending on the individual propensity and state of mind, discovering that a specific disease is in ones future can lead to positive changes or can lead to irrational fear. Take the example of Sergey Brin, the co-founder of Google and husband of Anne Wojcicki the co-founder of 23andMe. In 2008, Sergey learned that he carries the mutated LRRK2 gene, putting him at risk of developing Parkinson’s disease. Since there is currently no preventive treatment for Parkinson’s disease – the available dopamine-centric medications address the symptoms and not the cause of the disease – he decided to tilt the odds in his favor by starting a strict regimen of physical exercise designed to stimulate his brain’s motor and coordination functions that are affected in Parkinson’s disease. Sergey’s reaction might not be typical: he is after all a fundamentally positive person. Therefore, for the general public, counseling is, and should remain, an intrinsic part of genetic testing.

Beyond the personal psychological impact of learning about ones medical future, the issue of privacy of genetic information is also critical. Unlike traditional medical diagnostics which reflect a specific state of an individual at a given time, genetic information represents an unalterable and stable characteristic of an individual. I would argue that this characteristic of genetic information forces us to attribute ownership of genetic information solely to the individual and not to the medical practitioners. This represents a significant departure from the current practices and will require a major evolution of the medical community. Furthermore, genetic information poses an additional challenge because at any given time, it contains information of unknown utility. Indeed, the ability to associate disease risk with specific genetic features is still in its infancy. It is reasonable to assume that as the field evolves, the ability to interpret an individual’s genetic information will change substantially. Therefore, ownership of genetic information by an individual should not be limited to its current use but also to its future use: an individual should retain the right to decide whether his/her genetic information should be reanalyzed to account for updated genetic knowledge.